Inquisition Composition

Ok, quick Inquisition question... Can I combine SM and IG units together for an Inquisitor's army? Army Builder doesn't seem to like it when I bring them together, but I have this really cool idea for fluff that I want to use, and I'd like to bring in Ultramarines and some of my Ultramar Guard to form an Ultramar Inquisitor force (I'll have a background written up soon for it too ) So, what do you all think? Is SM and IG together in an Inquisitor's force too much? If I can come up with good fluff, is it game legal? Would you play against someone who had this type of force?

_________________A tiny portion of humanity turned its back on mankind in the waning days of the last Golden Age. Over one and a half centuries later, the PHR has emerged from the shadows as an unrecognisable civilisation, its people irrevocably changed. They are no longer simple human beings, they are post-humans - cyborgs.

I was reading this yesterday for something else, but i believe that to do this you either need to use the witch or deeamon hunters codex,which alow the use of a bunch of guard units, but not all. But looking at one of those codexis is the place to start. THere used to be an article on the GW site that talked about this but with the site change i do not know if it is still around

I don't think its legal, even with a WH or DH force, but it would be amazing to play all the same. If you can find some willing opponents I'm sure there won't be any problems to playing this type of army.

Looked it up, pg 25 in WH Codex and not sure what page in DH, but says,

"When using Allied or Inducted troops, only basic version of these troop types published in the appropriate Codex can be used. No variants of any kind can be incorporated. Either inducted Imperial Guard or allied Space Marines can be used in any one Witch Hunters army, but not both."

I guess I'll have to check out the DH book now... I would LOVE to be able to do this....

_________________A tiny portion of humanity turned its back on mankind in the waning days of the last Golden Age. Over one and a half centuries later, the PHR has emerged from the shadows as an unrecognisable civilisation, its people irrevocably changed. They are no longer simple human beings, they are post-humans - cyborgs.

What i meant was to play the guard as witch/deamon hunters, using inquisitorial guard. your army would have to be led by an "inquisitor" and you would have to use storm troopers as basic troops, but you would have pretty much the same tank options and such right?